At various times during the life of a well in a subterranean formation it is desirable to treat the well. Such treatments can include perforating, gravel packing, fracturing, and acidizing. These treatments generally involve filling the wellbore with a standing or circulating treatment fluid. Although high fluid permeability is an important characteristic of a hydrocarbon-producing formation, these treatments may be adversely effected by loss of treating fluid into the formations. For example, in an acidizing treatment it is desired to treat the least permeable formation to improve its permeability; however, the formation strata having the highest permeability will most likely consume a major portion of the treatment fluid leaving the least permeable formation strata virtually untreated. During fracturing treatments it is desirable to control loss of the treating fluid to the subterranean formation to maintain sufficient hydraulic pressure to propagate the fracture. During perforating operations, it is desirable to prevent fluids from entering the formation and damaging the formation. During gravel pack operations, it is desirable to recover expensive workover fluids from the wellbore after completion of the operation. The efficient performance of some treatments of the wellbore require temporarily reducing the permeability of formation to reduce the loss of treating fluid during the treatment. To effect control of the treatment fluids in the wellbore it is frequently useful to actuate, or otherwise activate or change a configuration of a flow path in a well. For example, it is beneficial to be able to open or close an opening or flow path in a well bore to be able to permit or prevent fluid flow through the flow path, when desired.
The present invention provides compositions, methods and apparatus whereby high strength dissolvable compositions may be used for accomplishing these purposes and others.